Probability of the 2~1S_0 — 2~3S_1 forbidden transition in the helium atom

摘要

The probability W of the forbidden magnetic-dipole 21S0 — 23S1 transition in the helium atom is calculated to be 6.11×10-8 s-1. An estimate is obtained of the number of atoms excited to the 21S0 state by a travelling wave which is in resonance with the frequency of this transition.